This invention relates to a filter assembly, and more particularly to a filter head for such an assembly for releasably accommodating a disposable filter cartridge.
Conventional filter assemblies include filter cartridges which house a filter media, such as activated carbon, and a corresponding filter head designed to releasably and sealingly accommodate the filter cartridge and to couple the cartridge to a fluid flow line. One type of presently available filter cartridges for such heads has a generally cylindrical extension at its upper end provided with multiple input and output flow channels that allow the fluid in the cartridge to be easily connected to the fluid flow line by a filter head. One example of such a filter assembly is disclosed in commonly assigned U.S. Pat. No. Re. 34,050, incorporated herein by reference. In such an assembly, the filter head is provided with at least one O-ring for separating the inflow from the filtered outflow.
Certain prior art filter heads of this type have disadvantages relating to the engagement of the cartridge with the filter head. U.S. Pat. No. 5,354,464 discloses a filter head designed for use with a cartridge using a pair of O-rings to separate the flow paths of the liquid in the filter head and to isolate the filter system flow from the ambient atmosphere. A significant drawback of such a filter head is that the O-rings, which protrude radially from the exterior of the filter cartridge closure, become deformed or misaligned when the filter cartridge is inserted into the filter head. Specifically, the O-rings catch or snag on openings in the central head chamber. This in turn can prevent the fluid flow paths from remaining separate, can reduce the life of the filter cartridge and can even inhibit fluid flow in the fluid flow path.
Furthermore, other prior art filter heads are designed for use with cartridges having three O-rings to separate the fluid flow paths and to isolate the filter system flow from the ambient atmosphere. One such filter head and corresponding cartridge is disclosed in commonly-assigned U.S. Pat. No. Re. 34,050. A feature of that filter assembly is the provision of a vent opening in the head to relieve any pressure in the head which would impede the insertion of the cartridge. Regardless, the greater the number of O-rings provided on the cartridge, the greater the chance of an O-ring becoming deformed or misaligned upon insertion into the filter head as described above.
Thus, there exists a need, in a filter assembly having a filter cartridge with a multiple fluid flow port closure, for a filter head featuring a solution to the problem of O-ring deformation or misalignment. There is also a need for a filter assembly having a filter head of a certain design optionally providing air escape through a vent, or without such a vent, when a filter cartridge is inserted into the filter head.
Accordingly, a first object of the present invention is to provide an improved filter head having a guide to properly align the seal members on the filter cartridge during insertion in the filter head, preventing such seal members from becoming deformed, misaligned, tom or broken.
Yet another object of the present invention is to provide an improved filter head that vents air upon insertion of the filter cartridge into the filter head, thus balancing the internal head pressure.
A further object of the present invention is to provide an improved filter head configured for easy installation of a disposable filter cartridge.
Other objects and advantages of the invention will become more apparent from the following description and accompanying drawings.